Surah An-Nur (The Light), Verse 60

وَالْقَوَاعِدُ مِنَ النِّسَآءِ الّٰتِیْ لَا یَرْجُوْنَ نِكَاحًا فَلَیْسَ عَلَیْهِنَّ جُنَاحٌ اَنْ یَّضَعْنَ ثِیَابَهُنَّ غَیْرَ مُتَبَرِّجٰتٍ بِزِیْنَةٍ وَاَنْ یَّسْتَعْفِفْنَ خَیْرٌ لَّهُنَّ وَاللّٰهُ سَمِیْعٌ عَلِیْمٌ ۟

Walqawaa'idu minan nisaaa'il laatee laa yarjoona nikaahan fa laisa 'alaihinna junaahun ai yada'na siyaabahunna ghaira mutabarrijaatin bi zeenah; wa ai yasta'fif na khairul lahunn; wallaahu Samee'un 'Aleem

“Such elderly women as are past the prospect of marriage,- there is no blame on them if they lay aside their (outer) garments, provided they make not a wanton display of their beauty: but it is best for them to be modest: and Allah is One Who sees and knows all things.”

Quran 24:60 (Yusuf Ali Translation)